Display device, electronic device, and method of manufacturing display device

ABSTRACT

There is provided a display device including: a first substrate that is a silicon substrate and on which a plurality of light-emitting elements is formed; a second substrate including, on a surface, a color filter layer including a plurality of color filters arrayed and a microlens layer including a plurality of microlenses arrayed that are layered in this order, the microlens layer being arranged to face the plurality of light-emitting elements with respect to the first substrate; and an adhesive layer that fills a gap between the first substrate and the second substrate for bonding the first substrate and the second substrate together.

TECHNICAL FIELD

The present disclosure relates to a display device, an electronicdevice, and a method of manufacturing a display device.

BACKGROUND ART

In a display device, to improve light extraction efficiency, a structurehas been devised in which a microlens (ML) is provided for each pixel inits light emission direction. For example, Patent Documents 1 and 2disclose an organic electroluminescence (EL) display device in which anML is provided for each pixel, the organic EL display device beingproduced by bonding, to a first substrate on which a plurality oflight-emitting elements is formed, a second substrate on which aplurality of the MLs is formed on a surface thereof such that theplurality of MLs faces the plurality of light-emitting elements.

CITATION LIST Patent Document Patent Document 1: Japanese PatentApplication Laid-Open No. 2014-120433 Patent Document 2: Japanese PatentApplication Laid-Open No. 2015-69700 SUMMARY OF THE INVENTION Problemsto be Solved by the Invention

In recent years, development has been actively conducted of anultra-small display device (also referred to as a microdisplay) mountedon electronic devices, for example, a head mounted display (HMD), anelectronic view finder (EVF) of a digital camera, and the like. In suchan ultra-small display device, to obtain a desired luminance, it isrequired to further improve the light extraction efficiency as comparedwith a larger display device. Thus, it is considered that theabove-described configuration in which the ML is provided for each pixelis particularly effective in such an ultra-small display device.

However, the technologies described in Patent Documents 1 and 2 aboveare considered to be intended for a medium display device mounted onelectronic devices, for example, a smartphone, a tablet personalcomputer (PC), and the like, and it is not intended for the ultra-smalldisplay device. Thus, even if the technologies described in PatentDocuments 1 and 2 above are applied as they are to an ultra-smalldisplay device, there is a possibility that the light extractionefficiency cannot be effectively improved.

The present disclosure therefore devises a novel and improved displaydevice, an electronic device, and a method of manufacturing a displaydevice capable of further improving the light extraction efficiency.

Solutions to Problems

According to the present disclosure, there is provided a display deviceincluding: a first substrate that is a silicon substrate and on which aplurality of light-emitting elements is formed; a second substrateincluding, on a surface, a color filter layer including a plurality ofcolor filters arrayed and a microlens layer including a plurality ofmicrolenses arrayed that are layered in this order, the microlens layerbeing arranged to face the plurality of light-emitting elements withrespect to the first substrate; and an adhesive layer that fills a gapbetween the first substrate and the second substrate for bonding thefirst substrate and the second substrate together.

According to the present disclosure, there is provided an electronicdevice including a display device that performs display on the basis ofan image signal, in which the display device includes: a first substratethat is a silicon substrate and on which a plurality of light-emittingelements is formed; a second substrate including, on a surface, a colorfilter layer including a plurality of color filters arrayed and amicrolens layer including a plurality of microlenses arrayed that arelayered in this order, the microlens layer being arranged to face theplurality of light-emitting elements with respect to the firstsubstrate; and an adhesive layer that fills a gap between the firstsubstrate and the second substrate for bonding the first substrate andthe second substrate together.

Furthermore, according to the present disclosure, there is provided amethod of manufacturing a display device, including: forming a pluralityof light-emitting elements on a first substrate that is a siliconsubstrate; layering, on a second substrate, a color filter layerincluding a plurality of color filters arrayed and a microlens layerincluding a plurality of microlenses arrayed, in this order; and bondingthe first substrate and the second substrate together to cause themicrolens layer to face the plurality of light-emitting elements.

According to the present disclosure, a facing CF type display device isprovided. To cope with miniaturization, a silicon substrate is used asthe first substrate. Furthermore, in the display device, the MLs areformed on the second substrate before the first substrate on thelight-emitting element side and the second substrate on the CF side arebonded together. As a result, there is no need to consider influence ofheat or the like on the light-emitting elements, and an existingtechnology can be applied as it is to a step of forming the MLs. Asdescribed above, according to the present disclosure, in a displaydevice capable of coping with miniaturization, the MLs can be formedwithout a significant increase in development cost, and the lightextraction efficiency can be improved.

Effects of the Invention

As described above, according to the present disclosure, the lightextraction efficiency can be further improved. Note that, theabove-described effect is not necessarily limited, and, in addition tothe above effect, or in place of the above effect, any of effectsdescribed in this specification, or other effects that can be graspedfrom the present specification may be exhibited.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating a configuration of a general OCCF typeorganic EL microdisplay.

FIG. 2 is a diagram illustrating a configuration of a display deviceaccording to the present embodiment.

FIG. 3 is a diagram illustrating a configuration of a first substrateimmediately before a step of being bonded, in the display deviceaccording to the present embodiment.

FIG. 4 is a diagram illustrating a configuration of a second substrateimmediately before the step of being bonded, in the display deviceaccording to the present embodiment.

FIG. 5 is a top view illustrating an array of CFs in a delta array as anexample of a method of arraying the CFs.

FIG. 6 is a top view illustrating the array of the CFs in a square arrayas another example of the method of arraying the CFs.

FIG. 7 is a diagram for explaining an effect of an ML in the displaydevice according to the present embodiment.

FIG. 8 is a diagram for explaining a method of forming an ML layer onthe second substrate.

FIG. 9 is a diagram for explaining the method of forming the ML layer onthe second substrate.

FIG. 10 is a diagram for explaining the method of forming the ML layeron the second substrate.

FIG. 11 is a diagram illustrating measurement results of values of X, Y,and Z in the CIE XYZ color system of emitted light, for an organic ELmicrodisplay according to the present embodiment.

FIG. 12 is a diagram illustrating measurement results of luminance ofthe emitted light, for the organic EL microdisplay according to thepresent embodiment.

FIG. 13 is a diagram illustrating an appearance of a digital camera thatis an example of an electronic device to which the display deviceaccording to the present embodiment can be applied.

FIG. 14 is a diagram illustrating an appearance of the digital camerathat is the example of the electronic device to which the display deviceaccording to the present embodiment can be applied.

FIG. 15 is a diagram illustrating an appearance of an HMD that isanother example of the electronic device to which the display deviceaccording to the present embodiment can be applied.

MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of the present disclosure will be described indetail below with reference to the accompanying drawings. Note that, inthe present specification and the drawings, constituents havingsubstantially the same functional configuration are denoted by the samereference signs, and redundant explanations are omitted.

Note that, in this specification, in a case where it is described that acertain layer and another layer are layered, the expression may mean astate in which these layers are layered in direct contact with eachother, and may also mean a state in which these layers are layered withanother layer interposed therebetween.

Note that, a technology according to the present disclosure can besuitably applied to a display device having a size smaller than a mediumsize (a so-called small display device, and an ultra-small displaydevice) among display devices. Thus, in the following description, anembodiment of the present disclosure will be described taking theultra-small display device as an example.

Here, in this specification, the ultra-small display device means adisplay device having a panel size of about 0.2 inches to about 2inches, for example. A pixel size of the ultra-small display device maybe, for example, equal to or less than about 20 μm. As described above,the ultra-small display device can be suitably mounted on, for example,an HMD, an EVF, or the like. Furthermore, the small display device meansa display device having a panel size of about 2 inches to about 7inches, for example. A pixel size of the small display device may be,for example, from about 30 μm to 70 μm. Furthermore, in the presentspecification, a medium display device means a display device having apanel size of about 7 inches to about 15 inches, for example. A pixelsize of the medium display device may be, for example, from about 50 μmto about 100 μm. A small or medium display device can be suitablymounted on, for example, a smartphone, a tablet PC, or the like.

Furthermore, in the following description, an organic EL display devicewill be described as an example. Note that, an ultra-small organic ELdisplay device is also referred to as an organic EL microdisplay, anorganic light emitting diode (OLED) microdisplay (MOLED), or the like.However, the present disclosure is not limited to such an example, andthe technology according to the present disclosure may be applied toanother type of display device as long as the display device has aconfiguration in which a CF can be arranged for each pixel.

Note that, the description will be made in the following order.

1. Background where the present disclosure has been conceived

2. Configuration of display device

3. Method of forming ML layer

4. Confirmation of effect

4-1. Relationship between ML thickness and light extraction efficiency

4-2. Relationship between gap between MLs and light extractionefficiency

5. Application examples

6. Supplement

1. Background where the Present Disclosure has been Conceived

Prior to description of a preferred embodiment of the presentdisclosure, a background will be described where the present inventorshave conceived the present disclosure.

As described above, in recent years, development has been activelyconducted of the ultra-small display device mounted on, for example, theHMD, the EVF, or the like. Above all, the organic EL display device canimplement high contrast and high speed response as compared with aliquid crystal display device, so that the organic EL display device(organic EL microdisplay) has attracted attention, as the ultra-smalldisplay device mounted on such electronic devices.

In the organic EL microdisplay, miniaturization of the pixel size hasbeen progressed to obtain further high definition, and it is stronglyrequired to improve the light extraction efficiency to achieve a desiredluminance. Here, for example, Patent Documents 1 and 2 describe aconfiguration in which an ML is provided immediately above alight-emitting element in an organic EL display device. The technologiesdescribed in Patent Documents 1 and 2 are considered to be for a mediumdisplay device; however, there is a possibility that the lightextraction efficiency can be improved by application of the technologyto the organic EL microdisplay. Furthermore, by providing the ML,leakage of light into adjacent pixels can be suppressed, in other words,occurrence of color mixing can also be suppressed.

On the other hand, in the organic EL microdisplay, there are a method ofemitting, for example, each color of RGB by a light-emitting element(so-called RGB coloring method), and a method in which a light-emittingelement emits white light and a color filter (CF) is used to implementemission of, for example, each color of RGB. Moreover, as the latterorganic EL microdisplay having the CF, a mainstream is the one producedby an on chip color filter (OCCF) method in which the CF is contiguouslyformed on a substrate on which a light-emitting element, a drive circuitof the light-emitting element, and the like are formed.

With reference to FIG. 1, a configuration will be described of a generalorganic EL microdisplay (hereinafter also referred to as an OCCF typeorganic EL microdisplay) produced by the OCCF method. FIG. 1 is adiagram illustrating a configuration of the general OCCF type organic ELmicrodisplay. FIG. 1 schematically illustrates a state of a crosssection parallel to a layering direction (vertical direction) of theOCCF type organic EL microdisplay. Furthermore, the display deviceillustrated in FIG. 1 is a top emission type organic EL microdisplay.

As illustrated in FIG. 1, a display device 2 that is an OCCF typeorganic EL microdisplay includes a first substrate 201 on which aplurality of light-emitting elements (organic EL elements) eachincluding an OLED and emitting white light is formed and a secondsubstrate 203 that are bonded together.

The first substrate 201 includes, for example, glass, resin, or thelike. On the first substrate 201, a drive circuit layer 205 is formedincluding a drive circuit for driving the light-emitting elements.

Then, on the drive circuit, a light-emitting element layer 210 includingthe plurality of light-emitting elements arrayed is formed with aninsulating layer 207 interposed therebetween. Specifically, on theinsulating layer 207, a first electrode 209 that functions as an anode,an organic layer 211 including an organic light-emitting material, and asecond electrode 213 that functions as a cathode are layered in thisorder. For simplicity, although not illustrated, the first electrode 209is patterned to be isolated from each other to correspond to each pixel.A layered structure of the first electrode 209, the organic layer 211,and the second electrode 213 in a portion corresponding to each isolatedpattern can correspond to one light-emitting element (in other words,one pixel). For each pattern of the first electrode 209, the drivecircuit is appropriately connected through a via (not illustrated)provided in the insulating layer 207, and the drive circuitappropriately applies a voltage to the first electrode 209, whereby eachlight-emitting element can be driven.

Note that, as described above, one pixel can be formed by onelight-emitting element; however, actually, in the display device 2, onesub-pixel corresponding to any color is formed by one light-emittingelement, and one pixel can be formed by a plurality of the sub-pixelscorresponding to each color. However, in the present specification, forconvenience for explanation, a light-emitting unit including onelight-emitting element will be simply referred to as a pixel.

On the second electrode 213, a protective film 215 including resin orthe like is layered. Then, a CF layer 217 is formed on the protectivefilm 215. In the CF layer 217, any of CFs of respective colors of RGB (ared CF 217R, a green CF 217G, and a blue CF 217B) is formedcorresponding to each light-emitting element.

The second substrate 203 is bonded to the CF layer 217 with a sealingresin film 219 including resin or the like interposed therebetween,whereby the display device 2 is produced.

In a case where the ML is to be mounted on the display device 2 that isthe OCCF type organic EL microdisplay as described above, a step offorming the ML is added before the CF layer 217 is formed or after theCF layer 217 is formed on the first substrate 201.

Here, in image sensors, it is widely practiced to form the MLimmediately above a photodiode (PD) to improve light collectionefficiency on the PD. Specifically, as a method of forming the ML on asubstrate in an image sensor, a method is generally used of processing alens material patterned by photolithography technology into a sphericalshape by a reflow step. If it is possible to apply the method of formingthe ML in such an image sensor to the step of forming the ML in thedisplay device 2, it is not necessary to newly develop a process, sothat it is useful from a viewpoint of reduction of development cost.

However, in the display device 2 that is the OCCF type organic ELmicrodisplay, in a case where the ML is to be formed by the method usedin the above-described image sensor, problems below may occur.

First, the first problem is that there is a possibility thatcharacteristics of the light-emitting elements are degraded by thereflow step. For example, there is a possibility that an organic ELelement that is a light-emitting element does not operate properly anylonger if exposed to a high temperature, and it is generally required tosuppress the temperature at lower than about 100° C. in a step performedafter formation of the organic EL element. However, in a processgenerally used for the image sensor, a reflow temperature during MLformation is from about 100° C. to 250° C. Thus, when the ML is formedby performing reflow at such a high temperature, there is a possibilitythat characteristics of the organic EL element is degraded.

Next, the second problem is that it is difficult to make the shape ofthe ML into a concave lens shape. Note that, in this specification,regarding the shape of the ML, the shape of the lens protruding towardthe light-emitting element is referred to as a concave lens shape, andthe shape of the lens protruding toward an opposite side to thelight-emitting element (in other words, a light emission direction side)is referred to as a convex lens shape.

In general, silicon nitride (SiN) is often used as the protective film215, and its refractive index is about 2.0. On the other hand, therefractive index of the lens material that is a material of the ML maybe from about 2.0 to 3.0, for example, when a material generally usedfor the ML of the image sensor is assumed. As described above, when thegeneral material is assumed, the refractive index of the protective film215 becomes smaller than the refractive index of the ML, so that theshape of ML is preferably set to a concave lens shape to efficientlycollect the emitted light from the light-emitting element.

However, in a case where the ML is formed on the substrate by using theabove-described method used for the image sensor, the shape of the MLbecomes a lens shape protruding to an opposite side to the substrateside. That is, in the display device 2, in a case where the ML is formedon the first substrate 201 by using the existing method used for theimage sensor as it is, the shape of the ML becomes a convex lens shape.Thus, it is impossible to efficiently collect the emitted light from thelight-emitting element. If a magnitude relationship can be reversedbetween the refractive indexes of the material of the protective film215 and the material of the ML, even if the shape of the ML is a convexlens shape, it is possible to collect the light efficiently; however,newly developing such a protective film 215 and the ML causes anincrease in the development cost, and is not preferable.

As described above, from a viewpoint of protecting the organic ELelement from the high temperature at the time of reflow, and from aviewpoint of the lens shape of the ML, in a case where the ML is to bemounted on the display device 2, it is difficult to use the existingmethod used for the image sensor as it is. As described above, in a casewhere the ML is to be formed for the OCCF type organic EL microdisplay,it becomes necessary to newly develop a process for forming the ML, ornewly develop a material for the ML, so that there is a possibility thatthe increase in the development cost is caused. Note that, for the CFlayer 217, similarly, when the CF layer 217 is to be formed by using theexisting method used for the image sensor as it is, the organic ELelement is exposed to the high temperature, so that, for the OCCF typeorganic EL microdisplay, it may become necessary to newly develop aprocess also for forming the CF layer 217.

As described above, it has been difficult to say that a method ofmounting the ML on the organic EL microdisplay has been sufficientlystudied so far. In view of such circumstances, as a result of conductionof intensive studies on the method of mounting the ML on the organic ELmicrodisplay, the present inventors have conceived the presentdisclosure. According to the present disclosure, the ML can be moresuitably formed, in the organic EL microdisplay. As a result, theorganic EL microdisplay with higher light extraction efficiency can beimplemented. Hereinafter, a preferred embodiment will be described ofthe present disclosure conceived by the present inventors.

2. Configuration of Display Device

With reference to FIG. 2, a configuration will be described of a displaydevice according to an embodiment of the present disclosure. FIG. 2 is adiagram illustrating the configuration of the display device accordingto the present embodiment. FIG. 2 schematically illustrates a state of across section parallel to a layering direction (vertical direction) ofthe display device according to the present embodiment. Furthermore, thedisplay device illustrated in FIG. 2 is a top emission type displaydevice.

Referring to FIG. 2, the display device 1 according to the presentembodiment mainly includes: a first substrate 101; a light-emittingelement layer 110 that is formed on the first substrate 101 and on whicha plurality of light-emitting elements each including an OLED andemitting white light is formed; an ML layer 121 provided above thelight-emitting element layer 110 and including a plurality of MLs 121 aarrayed; a CF layer 117 provided above the ML layer 121 and including aplurality of CFs 117R, 117B, and 117G arrayed; and a second substrate103 provided above the CF layer 117 and including a material transparentto light from the plurality of light-emitting elements.

Here, in the present embodiment, to the first substrate 101 on which thelight-emitting element layer 110 is formed, the second substrate 103 inwhich the CF layer 117 and the ML layer 121 are layered in this order onthe surface is bonded, whereby the display device 1 is produced. Thatis, the display device 1 is an organic EL microdisplay (also referred toas a facing CF type organic EL microdisplay) produced by a facing CFmethod. For example, a panel size of the display device 1 may be fromabout 0.2 inches to about 2 inches. Furthermore, for example, a pixelsize of the display device 1 may be equal to or less than about 20 μm.

Here, FIG. 3 is a diagram illustrating a configuration of the firstsubstrate 101 immediately before a step of being bonded, in the displaydevice 1 according to the present embodiment, and FIG. 4 is a diagramillustrating a configuration of the second substrate 103 immediatelybefore the step of being bonded, in the display device 1 according tothe present embodiment. Hereinafter, the configurations will bedescribed in order of the first substrate 101 and the second substrate103, with reference to FIGS. 3 and 4.

(Configuration of First Substrate)

The first substrate 101 includes silicon. On the first substrate 101, adrive circuit layer 105 is formed including a drive circuit for drivingthe light-emitting elements of the light-emitting element layer 110. Thedrive circuit includes, for example, a thin film transistor (TFT) andthe like.

Here, in general, in an organic EL display device of a medium size orlarger size, a glass substrate, a resin substrate, or the like is oftenused as the first substrate on which the light-emitting elements areformed. On the other hand, as described above, in the organic ELmicrodisplay, the miniaturization of the pixel size has been progressedto obtain further high definition, and along with this, the size of theTFT constituting the drive circuit, a wiring pitch of a wiring layer,and the like are also being miniaturized. In a case where the glasssubstrate or the resin substrate is used, fine processing required forsuch a high-definition organic EL microdisplay is difficult.

On the other hand, according to the present embodiment, by using asilicon substrate (silicon wafer) as the first substrate 101, the TFTand wiring can be more finely processed by using an existingsemiconductor process technology. For example, a TFT of several μm ordercan be formed. As described above, in the display device 1, by using thesilicon substrate as the first substrate 101, the high-definitionorganic EL microdisplay can be implemented.

On the drive circuit layer 105, the light-emitting element layer 110 isformed with the insulating layer 107 interposed therebetween. Note that,the insulating layer 107 may include various known materials that can beused as an interlayer insulating layer in a general organic EL display.For example, the insulating layer 107 can include silicon oxide (SiO₂ orthe like), SiN, insulating resin, or the like singly or in appropriatecombination. Furthermore, a method of forming the insulating layer 107is also not particularly limited, and for forming the insulating layer107, a known method can be used, such as a CVD method, a coating method,a sputtering method, or various printing methods.

The light-emitting element layer 110 includes a first electrode 109, anorganic layer 111 that functions as a light-emitting layer, and a secondelectrode 113 that are layered in this order on the insulating layer107. For simplicity, although not illustrated, the first electrode 109is patterned to be isolated from each other to correspond to each pixel.A layered structure of the first electrode 109, the organic layer 111,and the second electrode 113 in a portion corresponding to the isolatedpattern can correspond to one light-emitting element (in other words,one pixel). For each pattern of the first electrode 109, the drivecircuit is appropriately connected through a via (not illustrated)provided in the insulating layer 107, and the drive circuitappropriately applies a voltage to the first electrode 109, whereby eachlight-emitting element can be driven.

The organic layer 111 includes an organic light-emitting material, andis enabled to emit white light. A specific configuration of the organiclayer 111 is not limited, and may be various known configurations. Forexample, the organic layer 111 may have: a layered structure of a holetransport layer, a light-emitting layer, and an electron transportlayer; a layered structure of a hole transport layer and alight-emitting layer serving also as an electron transport layer; alayered structure of a hole injection layer, a hole transport layer, alight-emitting layer, an electron transport layer, and an electroninjection layer; or the like. Furthermore, in a case where these layeredstructures and the like are “tandem units”, the organic layer 111 mayhave a two-stage tandem structure in which a first tandem unit, aconnection layer, and a second tandem unit are layered. Alternatively,the organic layer 111 may have a tandem structure of three or morestages in which three or more tandem units are layered. In a case wherethe organic layer 111 includes a plurality of tandem units, by changingemission color of the light-emitting layer in red, green, and blue foreach tandem unit, the organic layer 111 can be obtained that emits whiteas a whole.

For example, the organic layer 111 is formed by vacuum evaporation of anorganic material. However, the present embodiment is not limited to suchan example, and the organic layer 111 may be formed by various knownmethods. An example of a method that can be used as a method of formingthe organic layer 111 includes: a physical vapor deposition method (PVDmethod) such as a vacuum evaporation method; a printing method such as ascreen printing method and an inkjet printing method; a laser transfermethod that transfers an organic layer by separating the organic layeron a laser absorption layer formed on a transfer substrate by emitting alaser to a layered structure of the laser absorption layer and theorganic layer; various coating methods; or the like.

The first electrode 109 functions as an anode. Since the display device1 is of a top emission type, the first electrode 109 includes a materialthat can reflect light from the organic layer 111. For example, thefirst electrode 109 includes an alloy of aluminum and neodymium (Al—Ndalloy). Furthermore, a film thickness of the first electrode 109 is, forexample, from about 0.1 μm to 1 μm. However, the present embodiment isnot limited to such an example, and the first electrode 109 can includevarious known materials used as a material of a light reflection sideelectrode that functions as an anode in a general organic EL displaydevice. Furthermore, the film thickness of the first electrode 109 isnot limited to the above example, and the first electrode 109 can beappropriately formed within a range of the film thickness generallyadopted in the organic EL display device.

For example, the first electrode 109 can include metal having a highwork function, such as platinum (Pt), gold (Au), silver (Ag), chromium(Cr), tungsten (W), nickel (Ni), copper (Cu), iron (Fe), cobalt (Co), ortantalum (Ta), or an alloy (for example, an Ag—Pd—Cu alloy containingsilver as a main component, palladium (Pd) of 0.3 mass % to 1 mass %,and copper of 0.3 mass % to 1 mass %, or an Al—Nd alloy). Alternatively,as the first electrode 109, a conductive material can be used having alow work function value and high light reflectance, such as aluminum oran alloy containing aluminum. In this case, it is preferable to improvethe hole injection property by providing an appropriate hole injectionlayer or the like on the first electrode 109. Alternatively, the firstelectrode 109 may have a structure in which a transparent conductivematerial having excellent hole injection characteristics, such as anindium tin oxide (ITO) or an indium zinc oxide (IZO), is layered on adielectric multilayer film, or a reflective film having high lightreflectivity such as aluminum.

The second electrode 113 functions as a cathode. Since the displaydevice 1 is of a top emission type, the second electrode 113 includes amaterial that can transmit light from the organic layer 111. Forexample, the second electrode 113 includes an alloy of magnesium andsilver (Mg—Ag alloy). Furthermore, a film thickness of the secondelectrode 113 is, for example, about 10 nm. However, the presentembodiment is not limited to such an example, and the second electrode113 can include various known materials used as a material of a lighttransmission side electrode that functions as a cathode in a generalorganic EL display device. Furthermore, the thickness of the secondelectrode 113 is not limited to the above example, and the secondelectrode 113 can be appropriately formed within a range of the filmthickness generally adopted in the organic EL display device.

For example, the second electrode 113 can include aluminum, silver,magnesium, calcium (Ca), sodium (Na), strontium (Sr), an alloy of analkali metal and silver, an alloy of alkali-earth metal and silver (forexample, an alloy of magnesium and silver (Mg—Ag alloy)), an alloy ofmagnesium and calcium (Mg—Ca alloy), an alloy of aluminum and lithium(Al—Li alloy), or the like. In a case where these materials are used asa single layer, the film thickness of the second electrode 113 is, forexample, from about 4 nm to 50 nm. Alternatively, the second electrode113 may have a structure in which the above-described material layer anda transparent electrode (for example, from about 30 nm to 1 μm inthickness) including, for example, ITO or IZO are layered from theorganic layer 111 side. In the case of such a layered structure, thethickness of the above-described material layer can also be reduced to,for example, from about 1 nm to 4 nm. Alternatively, the secondelectrode 113 may include only the transparent electrode. Alternatively,to the second electrode 113, a bus electrode (auxiliary electrode) maybe provided including a low resistance material such as aluminum, analuminum alloy, silver, a silver alloy, copper, a copper alloy, gold, agold alloy, or the like, to achieve a low resistance of the secondelectrode 113 as a whole.

For example, the first electrode 109 and the second electrode 113 areformed by depositing a material with a predetermined thickness by avacuum evaporation method, and then patterning the film by an etchingmethod. However, the present embodiment is not limited to such anexample, and the first electrode 109 and the second electrode 113 may beformed by various known methods. An example of a method of forming thefirst electrode 109 and the second electrode 113 includes: anevaporation method including an electron beam evaporation method, a hotfilament evaporation method, and a vacuum evaporation method; asputtering method; a chemical vapor deposition method (CVD method); ametal organic chemical vapor deposition method (MOCVD method); acombination of an ion plating method and an etching method; variousprinting methods (for example, a screen printing method, an inkjetprinting method, a metal mask printing method, or the like); a platingmethod (an electroplating method, an electroless plating method, or thelike); a lift-off method; a laser ablation method; a sol-gel method; orthe like.

(Configuration of Second Substrate)

The second substrate 103 includes quartz glass. However, the presentembodiment is not limited to such an example, and various knownmaterials may be used as the second substrate 103. For example, thesecond substrate 103 can include various glass substrates, organicpolymer substrates, or the like. However, since the display device 1 isof a top emission type, the second substrate 103 can include a materialhaving high light transmittance that can suitably transmit the emittedlight from the light-emitting element.

On the second substrate 103, the CF layer 117 is formed. A filmthickness of the CF layer 117 is, for example, from about 0.5 μm toabout 2.0 μm. In the CF layer 117, after the first substrate 101 and thesecond substrate 103 are bonded together, any of CFs of respectivecolors of RGB (the red CF 117R, the green CF 117G, and the blue CF 117B)is formed at a portion corresponding to each light-emitting element.That is, after the first substrate 101 and the second substrate 103 arebonded together, any one of the CF 117R, CF 117G, and CF 117B isarranged for one light-emitting element. Note that, in the followingdescription, in a case where it is unnecessary to distinguish the CF117R, CF 117G, and CF 117B from each other, one or more of them is alsoreferred to simply as CF 117 a.

For formation of the CF layer 117, various known materials and processescan be applied used for forming the CF in the image sensor. For example,the CF layer 117 can be formed by exposing and developing a resistmaterial in a predetermined shape by a photolithography technology.

Note that, a method of arraying the CFs 117 a is not limited. Forexample, the arraying method may be various known arraying methods suchas a stripe array, a delta array, a square array, or the like. FIG. 5 isa top view illustrating an array of the CFs 117 a in the delta array asan example of the method of arraying the CFs 117 a. FIG. 6 is a top viewillustrating the array of the CFs 117 a in the square array as anotherexample of the method of arraying the CFs 117 a. In the square array,one pixel can include the red CF 117R corresponding to one sub-pixel,the green CF 117G corresponding to one sub-pixel, and the blue CF 117Bcorresponding to two sub-pixels.

A planarizing film 119 is layered on the CF layer 117. The planarizingfilm 119 includes a resin-based material (for example, a mixture ofnovolak and acrylic resin, acrylic resin, styrene resin, or the like).

Then, the ML layer 121 is formed on the planarizing film 119. In the MLlayer 121, the MLs 121 a are formed such that the MLs 121 a arepositioned at portions corresponding to respective CFs 117 a of the CFlayer 117. That is, one ML 121 a is arranged for one CF 117 a.

For example, in the present embodiment, each ML 121 a can be formed in ashape that substantially inscribes the corresponding CF 117 a as viewedfrom above. In this case, the adjacent MLs 121 a are formed to be incontact with each other. However, the present embodiment is not limitedto such an example, and the ML 121 a does not have to be completelyinscribed in the CF 117 a as viewed from above, and it may be formedsomewhat small. In this case, there is a gap between the adjacent MLs121 a; however, as a result of studies by the present inventors, even ifsuch a gap exists, as long as the gap is within a predetermined range,it has been found that the ML 121 a sufficiently performs a function ofcollecting the emitted light (details will be described below (4.Confirmation of effect)). Thus, in the present embodiment, as describedabove, even if each ML 121 a is formed such that a gap exists betweenthe MLs 121 a, the gap is appropriately adjusted, whereby an effect canbe obtained of improving the light extraction efficiency.

Note that, depending on the method of arraying the CFs 117 a, the shapeof each CF 117 a differs as viewed from above, so that the shape of ML121 a also differs. For example, in the case of the delta array, theshape of the CF 117 a is substantially a regular hexagon for each color.Thus, in this case, the shape of the ML 121 a may be substantially aperfect circle, corresponding to the shape of the CF 117 a. On the otherhand, for example, in the case of the stripe array, the shape of the CF117 a is substantially rectangular for each color. Thus, in this case,the shape of the ML 121 a may be substantially elliptical, correspondingto the shape of the CF 117 a. Furthermore, the shape of the ML 121 a isnot limited to a circular shape, and may be a substantially square shapeor a shape close to a square shape (a rectangle in which each vertex isrounded). Since it is considered that the shape of the optimum ML 121 athat can obtain high light collection efficiency varies depending on theshape of the CF 117 a, in other words, the shape of the pixel, the shapeof the ML 121 a may be appropriately determined in accordance with theshape of the CF 117 a.

For formation of the ML layer 121 (in other words, formation of the ML121 a), for example, various known materials and processes can beapplied used for forming the ML in the image sensor. For example, as thematerial of the ML layer 121, a melt flow type microlens resist materialused in an image sensor is used, and the ML layer 121 can be formedthrough patterning by photolithography and the reflow step. Thus, on thesecond substrate 103, the ML 121 a has a convex shape protruding towardthe opposite side to the second substrate 103. Note that, details willbe described later of methods of forming the planarizing film 119 andthe ML layer 121.

In a state in which each layer up to the light-emitting element layer110 is formed on the first substrate 101 as illustrated in FIG. 3 andeach layer up to the ML layer 121 is formed on the second substrate 103,the first substrate 101 and the second substrate 103 are bonded togetherwith an adhesive layer 115 including a filler interposed therebetweensuch that the ML layer 121 faces the light-emitting element layer 110.As a result, the display device 1 is produced. In this case, asdescribed above, on the second substrate 103, since each ML 121 a isformed to have a convex shape protruding toward the opposite side to thesecond substrate 103, each ML 121 a has a lens shape (in other words, aconcave lens shape) protruding toward each corresponding light-emittingelement after the first substrate 101 and the second substrate 103 arebonded together.

Note that, as the filler of the adhesive layer 115, a material is usedwhose refractive index is lower than the refractive index of the MLlayer 121. For example, in a case where the above-described melt flowtype microlens resist material is used as the material of the ML layer121, since the refractive index of the resist material is about 3.0, aresin-based material is used as the filler, for example, epoxy resin,acrylic resin, or the like whose refractive index is about 1.5.

The configuration has been described above of the display device 1according to the present embodiment. As described above, the displaydevice 1 is the facing CF type organic EL microdisplay, and the ML layer121 is formed on the second substrate 103 on which the CF layer 117 isformed. Thus, even if the ML layer 121 is formed through a relativelyhigh temperature reflow step, the step does not affect thelight-emitting element of the light-emitting element layer 110. The MLlayer 121 can therefore be formed by using existing materials andmethods, for example, materials and methods used for the image sensor,and the like, so that the development cost can be significantly reduced.Furthermore, the CF layer 117 can also be formed by applying materials,methods, and the like used for the image sensor, for example, so thatthe development cost can be further reduced. As described above,according to the present embodiment, the display device 1 can beimplemented in which the light extraction efficiency is improved by theML layer 121 while the development cost is suppressed. Furthermore, theML layer 121 is provided, whereby leakage of light into adjacent pixelsis suppressed, so that the occurrence of color mixing can also besuppressed.

Note that, as a method of improving the light extraction efficiency inthe facing CF type organic EL microdisplay such as the display device 1,it is conceivable to thin the CF layer. However, when the CF layer issimply thinned, chromaticity is decreased, and color reproducibility isdegraded. With respect to such circumstances, in the present embodiment,the CF layer 117 is thinned to, for example, equal to or less than about2.0 μm, and the ML layer 121 is also formed. As a result, the emittedlight from each light-emitting element is collected by each ML 121 a andpasses through the CF 117 a corresponding to the light-emitting element,so that the light extraction efficiency can be improved withoutdegradation of the color reproducibility.

Furthermore, in formation of the ML layer 121 on the second substrate103, if the ML layer 121 is formed by using an existing method, forexample, the reflow or the like, the ML 121 a has a shape protrudingtoward the opposite side to the second substrate 103. When the secondsubstrate 103 on which the ML layer 121 is formed is bonded to the firstsubstrate 101 such that the ML layer 121 faces the light-emittingelement layer 110, the ML 121 a resultantly has a concave lens shape. Asdescribed above, in the display device 1, the ML 121 a having theconcave lens shape can be easily formed by using the existing method.

At this time, in the present embodiment, the filler constituting theadhesive layer 115 and the material of the ML layer 121 are selectedsuch that the refractive index of the adhesive layer 115 that is a layerbetween the light-emitting element and the ML 121 a becomes lower thanthe refractive index of the ML 121 a. Thus, the ML 121 a having theconcave lens shape is formed, whereby the light from the light-emittingelement can be efficiently collected by the ML 121 a as illustrated inFIG. 7. That is, the light extraction efficiency can be improved. FIG. 7is a diagram for explaining an effect of the ML 121 a in the displaydevice 1 according to the present embodiment. In FIG. 7, a part of thedisplay device 1 illustrated in FIG. 2 is extracted and illustrated, anda state is illustrated by arrows schematically in which the emittedlight from a light-emitting element is collected by the ML 121 a, andtransmitted through the CF 117R, 117G, or 117B corresponding to thelight-emitting element and the second substrate 103, and is extractedtoward the outside.

Note that, generally, in the facing CF type organic EL display device,when the substrate on which the light-emitting element is formed and thesubstrate on which the CF is formed are bonded together, alignmentaccuracy between the light-emitting element and the CF can be a problem.To perform the alignment with high accuracy, it can be said that theOCCF method is preferable in which the light-emitting element and the CFare formed on the same substrate. However, in the case of theultra-small organic EL display device, even with the facing CF method,the size of the panel is small, so that alignment of the light-emittingelement and the CF can be performed with high accuracy as compared witha medium or larger organic EL display device, for example. As describedabove, since the display device 1 is the ultra-small organic EL displaydevice, the alignment accuracy can be maintained between thelight-emitting element and the CF 117 a even if the display device 1 isproduced by the facing CF method. In other words, the configuration ofthe above-described facing CF method organic EL display device can besuitably applied to the ultra-small organic EL display device such asthe display device 1.

3. Method of Forming ML Layer

The method of forming the ML layer 121 on the second substrate 103described above will be described in more detail with reference to FIGS.8 to 10. FIGS. 8 to 10 are diagrams for explaining the method of formingthe ML layer 121 on the second substrate 103. In FIGS. 8 to 10, a crosssection parallel to the layering direction (vertical direction) of theconfiguration of the second substrate 103 is schematically illustratedin the order of steps in a producing method of the configuration, and aprocess flow in the producing method is represented.

As described above, when the CF layer 117 is formed on the secondsubstrate 103, the planarizing film 119 is layered thereon (FIG. 8). Afilm thickness of the planarizing film 119 is, for example, equal to orless than about 10 μm. Furthermore, the planarizing film 119 includes amaterial having a refractive index of, for example, from about 1.0 to2.5. An example of a material of the planarizing film 119 that canimplement such a refractive index includes a mixture of novolak andacrylic resin, acrylic resin, styrene resin, or the like. Note that, ina case where the CF layer 117 is formed to have sufficient flatness, theplanarizing film 119 does not have to be layered.

Next, a material (lens material) of the ML 121 a is deposited on theplanarizing film 119. Since a film thickness of the lens material is afactor that can determine a height and a curvature of the ML 121 a, thefilm thickness is appropriately determined so that the shape of the ML121 a to obtain a desired light collection efficiency can beimplemented. For example, the film thickness of the lens material can beappropriately determined within a range of 0.1 μm to 5.0 μm.Furthermore, as the lens material, a material used for the ML of theimage sensor may be applied as it is. For example, as the lens material,the melt flow type microlens resist material used in the image sensorcan be used. The refractive index of the resist material is about 3.0 asdescribed above.

Next, with photolithography technology, a lens material 123 deposited ispatterned by leaving only a portion where the ML 121 a is formed (inother words, a portion directly above each CF 117 a) (FIG. 9).Specifically, after an exposure step and a development step areperformed, bleaching processing of a photosensitive material by UV lightis performed. In the exposure step, for example, i-ray exposure isperformed.

Note that, by adjusting a pattern of the lens material 123 in apatterning step of the lens material 123, it is possible to control theshape of the ML 121 a after the formation as viewed from above, and thegap between the adjacent MLs 121 a. The lens material 123 is patternedto obtain a desired shape of the ML 121 a and a gap between the MLs 121a by predicting a change in shape in the reflow step as described later.

Next, the reflow is performed of the lens material 123 patterned,whereby the ML 121 a (in other words, the ML layer 121) is formed (FIG.10). The reflow temperature is from about 100° C. to 250° C.Furthermore, the reflow may also be performed by multi-stage heattreatment or temperature raising treatment.

Note that, after the ML 121 a is formed, an oxide film may be formed onthe surface thereof. For example, the oxide film can be deposited in arange of equal to or less than 1000 nm. The oxide film functions as alow reflection film that suppresses reflection of light at the ML 121 a.Such an oxide film is provided, whereby a rate decreases at which theemitted light from the light-emitting element is reflected on thesurface of the ML 121 a, and the light extraction efficiency can befurther improved.

The method of forming the ML layer 121 has been described above. Notethat, in the above description, the ML layer 121 is formed by aso-called melt flow method using the reflow; however, in the presentembodiment, the method of forming the ML layer 121 is not limited tosuch an example, and various known methods may be applied used informing the ML in the image sensor generally. For example, the ML layer121 may be formed by an etch back method. In the etch back method, afterthe lens material is deposited, resist reflecting the shape of the lens121 a (for example, a hemispherical shape) is formed thereon, and thelens 121 a is formed by performing etch back.

4. Confirmation of Effect

(4-1. Relationship Between ML Thickness and Light Extraction Efficiency)

Results will be described of an experiment conducted by the presentinventors to confirm the effect of improving the light extractionefficiency by the display device 1 according to the present embodimentdescribed above. In the experiment, a sample was produced of an organicEL microdisplay having a configuration similar to that of the displaydevice 1 according to the present embodiment illustrated in FIG. 2, thesample was actually driven, and regarding light emitted from the displaysurface, values of X, Y, and Z in the CIE XYZ color system were measured(note that, the value of Y corresponds to luminance). In the sample, thepixel size was 7.8 μm×7.8 μm. The array of the CFs was the square array,and one pixel was formed by a total of four sub-pixels of one redsub-pixel, one green sub-pixel, and two blue sub-pixels. The ML layerwas formed by the melt flow method. The gap between adjacent MLs was1000 nm.

In this experiment, a plurality of samples having mutually differentthickness of the ML layer (in other words, the height of the ML.Hereinafter, also referred to as ML thickness) was produced, and thevalues of X, Y, and Z were measured for each of the samples. The resultsare illustrated in FIG. 11. FIG. 11 is a diagram illustratingmeasurement results of the values of X, Y, and Z in the CIE XYZ colorsystem of the emitted light, for the organic EL microdisplay accordingto the present embodiment. In FIG. 11, the horizontal axis indicates theML thickness, and the vertical axis indicates measured values of X, Y,and Z, and a relationship is plotted between the ML thickness and themeasured value. Note that, as the value of the vertical axis, a relativevalue is plotted assuming that the value is 1 in a case where the MLlayer is not provided. It can be said that the value of the verticalaxis indicates an improvement rate (efficiency improvement rate) in thelight extraction efficiency, with the value in the case where the MLlayer is not provided, as a reference.

Referring to FIG. 11, it can be confirmed that the light extractionefficiency is improved by forming the ML layer, at least in a MLthickness range of equal to or less than about 2000 nm. In particular,in the samples used in this experiment, peaks were confirmed in theefficiency improvement rate at a point where the ML thickness was around1000 nm and a point where the ML thickness was around 1800 nm.Specifically, focusing on white light emission (X+Y+Z), it was confirmedthat the light extraction efficiency was improved by 1.2 times and 1.3times, respectively, at the point where the ML thickness was around 1000nm and the point where the ML thickness was around 1800 nm, as comparedwith the case where the ML layer was not provided. The results indicatethat the light extraction efficiency has dependence on the ML thickness,and the peaks exist at specific ML thicknesses. From the results, whenproducing the display device 1 according to the present embodiment,considering the relationship between the light extraction efficiency andthe ML thickness, the ML layer is designed so that its thickness is anappropriate value, whereby the light extraction efficiency can befurther improved.

Furthermore, as illustrated in FIG. 11, in the samples used in thisexperiment, a significant decrease was seen in the values of X, Y, and Zat a point where the ML thickness was around 2400 nm. In particular, thevalue of X was lower than that in the case where the ML layer was notprovided. The results indicate that when the ML thickness becomes toolarge, it is difficult to obtain the effect of improving the lightextraction efficiency, and the light extraction efficiency ratherdecreases depending on the color of the emitted light. The resultsindicate that in the display device 1 according to the presentembodiment, by designing the ML layer considering such an upper limit ofthe ML thickness for each color of light emission, the light extractionefficiency can be more efficiently improved.

(4-2. Relationship Between Gap Between MLs and Light ExtractionEfficiency)

Results will be described of an experiment conducted by the presentinventors to confirm influence of the gap between the adjacent MLs 121 aon the light extraction efficiency in the display device 1 according tothe present embodiment. In the experiment, a sample was produced of anorganic EL microdisplay having a configuration similar to that of thedisplay device 1 according to the present embodiment illustrated in FIG.2, the sample was actually driven, and regarding light emitted from thedisplay surface, luminance was measured. In the sample, the pixel sizewas 7.8 μm×7.8 μm. The array of the CFs was the square array, and onepixel was formed by a total of four sub-pixels of one red sub-pixel, onegreen sub-pixel, and two blue sub-pixels. The ML layer was formed by themelt flow method.

In this experiment, a plurality of samples having mutually differentgaps between the MLs was produced, and the luminance was measured foreach of the samples. The results are illustrated in FIG. 12. FIG. 12 isa diagram illustrating measurement results of the luminance of theemitted light of the organic EL microdisplay according to the presentembodiment. In FIG. 12, the horizontal axis indicates the gap betweenthe MLs, the vertical axis indicates a measured value of the luminance,and a relationship is plotted between the gap and the measured value.Furthermore, in this experiment, for each sample having a predeterminedgap between the MLs, samples were also produced in which the shape ofthe ML was changed as viewed from above, and the luminance was similarlymeasured also for these samples. In FIG. 12, as an example of theexperiment results, a result for a sample whose ML shape issubstantially square is plotted with a square marker, and a result for asample whose ML shape is substantially a perfect circle is plotted witha circle marker.

Referring to FIG. 12, in both of the sample whose ML shape issubstantially square and the sample whose ML shape is substantially theperfect circle, it can be confirmed that the luminance does notsubstantially change even if the gap between the MLs is changed. Theresults indicate that the light extraction efficiency does notsubstantially change even if the gap between the MLs is changed within apredetermined range. However, although not illustrated in FIG. 15, ifthe gap between the MLs becomes too large, the size of the ML in theplane decreases accordingly, so that it becomes difficult for theemitted light from the light-emitting element to enter the ML, and it isconsidered that the luminance decreases. From the results, whenproducing the display device 1 according to the present embodiment, itis important to design the ML layer to cause the gap between the MLs tofall within an appropriate range in which the effect of improving thelight extraction efficiency can be reliably obtained, by considering therelationship between the light extraction efficiency and the gap betweenthe MLs.

5. Application Examples

An application example will be described of the display device 1according to the present embodiment described above. Here, some exampleswill be described of an electronic device to which the above-describeddisplay device 1 can be applied.

FIGS. 13 and 14 are diagrams each illustrating an appearance of adigital camera that is an example of the electronic device to which thedisplay device 1 according to the present embodiment can be applied.FIG. 13 illustrates the appearance of the digital camera viewed from thefront (subject side), and FIG. 14 illustrates the appearance of thedigital camera viewed from the back. As illustrated in FIGS. 13 and 14,a digital camera 311 includes a main body (camera body) 313, aninterchangeable lens unit 315, a grip 317 gripped by a user at the timeof photographing, a monitor 319 that displays various kinds ofinformation, and an EVF 321 that displays a through image to be observedby the user at the time of photographing. The EVF 321 can include thedisplay device 1 according to the present embodiment.

FIG. 15 is a diagram illustrating an appearance of an HMD that isanother example of the electronic device to which the display device 1according to the present embodiment can be applied. As illustrated inFIG. 15, an HMD 331 includes a glasses-shaped display unit 333 thatdisplays various kinds of information, and an ear hook unit 335 to behooked to the user's ear at the time of wearing. The display unit 333can include the display device 1 according to the present embodiment.

Some examples have been described above of the electronic device towhich the display device 1 according to the present embodiment can beapplied. Note that, the electronic device to which the display device 1can be applied is not limited to those exemplified above, and thedisplay device 1 can be applied as a display device of any electronicdevice, as long as it is an electronic device on which a so-calledmicrodisplay can be mounted, for example, a glasses-shaped wearabledevice, or the like.

6. Supplement

The preferred embodiments of the present disclosure have been describedabove in detail with reference to the accompanying drawings; however,the technical scope of the present disclosure is not limited to suchexamples. It is obvious that persons having ordinary knowledge in thetechnical field of the present disclosure can conceive variousmodification examples or correction examples within the scope of thetechnical idea described in the claims, and it is understood that themodification examples or correction examples also belong to thetechnical scope of the present disclosure.

For example, in the above embodiment, in the display device 1, one ML121 a is arranged for one pixel; however, the technology according tothe present disclosure is not limited to such an example. For example,the plurality of MLs 121 a may be arranged for one pixel.

Furthermore, for example, in the above embodiment, the display device 1is an organic EL microdisplay; however, the technology according to thepresent disclosure is not limited to such an example. For example, thedisplay device according to the present disclosure may be a smallorganic EL display device. In a case where the display device accordingto the present disclosure is the small organic EL display device, thedisplay device can be mounted as a monitor of an electronic device suchas a smartphone, a tablet PC, a digital camera, an electronic book, apersonal digital assistant (PDA), or a game device. The display deviceaccording to the present disclosure can also be applied to a displaydevice mounted on an electronic device in any field in which display isperformed on the basis of an image signal input from the outside or animage signal generated in the inside.

Furthermore, the effects described in the present specification aremerely illustrative or exemplary and not restrictive. That is, thetechnology according to the present disclosure can exhibit other effectsobvious to those skilled in the art from the description of the presentspecification together with the above-described effects or in place ofthe above effects.

Note that, the following configurations also belong to the technicalscope of the present disclosure.

(1)

A display device including:

a first substrate that is a silicon substrate and on which a pluralityof light-emitting elements is formed;

a second substrate including, on a surface, a color filter layerincluding a plurality of color filters arrayed and a microlens layerincluding a plurality of microlenses arrayed that are layered in thisorder, the microlens layer being arranged to face the plurality oflight-emitting elements with respect to the first substrate; and

an adhesive layer that fills a gap between the first substrate and thesecond substrate for bonding the first substrate and the secondsubstrate together.

(2)

The display device according to (1), in which each of the microlenseshas a convex shape protruding toward a corresponding one of thelight-emitting elements.

(3)

The display device according to (1) or (2), in which

a refractive index of a material of the adhesive layer is smaller than arefractive index of a material of the microlens layer.

(4)

The display device according to any one of (1) to (3), in which

the display device is a microdisplay having a panel size of about 0.2inches to about 2 inches.

(5)

The display device according to any one of (1) to (4), in which

a pixel size of the display device is equal to or less than about 20 μm.

(6)

The display device according to any one of (1) to (5), in which

an array of the color filters is a square array.

(7)

The display device according to any one of (1) to (5), in which

an array of the color filters is a delta array.

(8)

The display device according to any one of (1) to (7), in which

a shape of each of the microlenses as viewed from a layering directionis substantially a perfect circle.

(9)

The display device according to any one of (1) to (7), in which

a shape of each of the microlenses as viewed from a layering directionis substantially square shape.

(10)

An electronic device including

a display device that performs display on the basis of an image signal,in which

the display device includes

a first substrate that is a silicon substrate and on which a pluralityof light-emitting elements is formed,

a second substrate including, on a surface, a color filter layerincluding a plurality of color filters arrayed and a microlens layerincluding a plurality of microlenses arrayed that are layered in thisorder, the microlens layer being arranged to face the plurality oflight-emitting elements with respect to the first substrate, and

an adhesive layer that fills a gap between the first substrate and thesecond substrate for bonding the first substrate and the secondsubstrate together.

(11)

A method of manufacturing a display device, including:

forming a plurality of light-emitting elements on a first substrate thatis a silicon substrate;

layering, on a second substrate, a color filter layer including aplurality of color filters arrayed and a microlens layer including aplurality of microlenses arrayed, in this order; and

bonding the first substrate and the second substrate together to causethe microlens layer to face the plurality of light-emitting elements.

REFERENCE SIGNS LIST

-   1, 2 Display device-   101, 201 First substrate-   103, 203 Second substrate-   105, 205 Drive circuit layer-   107, 207 Insulating layer-   109, 209 First electrode-   110, 210 Light-emitting element layer-   111, 211 Organic layer-   113, 213 Second electrode-   115 Adhesive layer-   117, 217 CF layer-   119 Planarizing film-   121 ML layer-   121 a ML-   123 Lens material-   215 Protective film-   219 Sealing resin film-   15

1. A display device comprising: a first substrate that is a siliconsubstrate and on which a plurality of light-emitting elements is formed;a second substrate including, on a surface, a color filter layerincluding a plurality of color filters arrayed and a microlens layerincluding a plurality of microlenses arrayed that are layered in thisorder, the microlens layer being arranged to face the plurality oflight-emitting elements with respect to the first substrate; and anadhesive layer that fills a gap between the first substrate and thesecond substrate for bonding the first substrate and the secondsubstrate together.
 2. The display device according to claim 1, whereineach of the microlenses has a convex shape protruding toward acorresponding one of the light-emitting elements.
 3. The display deviceaccording to claim 2, wherein a refractive index of a material of theadhesive layer is smaller than a refractive index of a material of themicrolens layer.
 4. The display device according to claim 1, wherein thedisplay device is a microdisplay having a panel size of about 0.2 inchesto about 2 inches.
 5. The display device according to claim 4, wherein apixel size of the display device is equal to or less than about 20 μm.6. The display device according to claim 1, wherein an array of thecolor filters is a square array.
 7. The display device according toclaim 1, wherein an array of the color filters is a delta array.
 8. Thedisplay device according to claim 1, wherein a shape of each of themicrolenses as viewed from a layering direction is substantially aperfect circle.
 9. The display device according to claim 1, wherein ashape of each of the microlenses as viewed from a layering direction issubstantially square shape.
 10. An electronic device comprising adisplay device that performs display on a basis of an image signal,wherein the display device includes a first substrate that is a siliconsubstrate and on which a plurality of light-emitting elements is formed,a second substrate including, on a surface, a color filter layerincluding a plurality of color filters arrayed and a microlens layerincluding a plurality of microlenses arrayed that are layered in thisorder, the microlens layer being arranged to face the plurality oflight-emitting elements with respect to the first substrate, and anadhesive layer that fills a gap between the first substrate and thesecond substrate for bonding the first substrate and the secondsubstrate together.
 11. A method of manufacturing a display device,comprising: forming a plurality of light-emitting elements on a firstsubstrate that is a silicon substrate; layering, on a second substrate,a color filter layer including a plurality of color filters arrayed anda microlens layer including a plurality of microlenses arrayed, in thisorder; and bonding the first substrate and the second substrate togetherto cause the microlens layer to face the plurality of light-emittingelements.